1. Field of the Invention
The present invention relates to a numerical control apparatus for a composite working machine which is capable of turning and milling.
2. Description of the Prior Art
When a work is subjected to a series of working processes, a plurality of machine tools corresponding to these working processes are usually required. For example, if a work is to be turned and then milled, it must be first mounted on a lathe for a desired turning process and after the turning process, it must be removed from the lathe and mounted on a milling machine for a desired milling process.
In this way, a work which is subjected to a plurality of different processes requires a corresponding plurality of machine tools and therefore, it takes more man-hours for work mounting, setup, and other steps for these different machine tools, which may significantly degrade the working efficiency. In addition, there were disadvantages that more machine tools required more time and labor to service and maintain them.
To overcome these disadvantages of the prior art, a composite working machine has been developed which is capable of both turning and milling by itself.
A conventional numerical control apparatus used to control such a composite working machine which performs both turning and milling, has been originally designed to control only a lathe system. FIG. 4 is a functional block diagram of such a conventional numerical control apparatus for a composite working machine.
A machining program entered by a manual input or from a external device 72 through a reader/puncher interface 15 is stored in a program memory 100b. Based on the stored machining program, a numerical controller for turning 100a performs interpolation and axis control and drivingly controls a spindle motor 125 through a spindle amplifier 115 as well as X-axis and Z-axis servo motors 121 and 122 through X-axis and Z-axis servo amplifiers 111 and 112, respectively, to perform turning.
When milling is performed, the numerical controller also drivingly controls through a servo amplifier 113 a C-axis servo motor 123 which controls the spindle rotational position, as well as X-axis, Y-axis, and Z-axis servo motors 121, 124, and 122 through servo amplifiers 111, 114, and 112, respectively, to perform milling.
In general, preparatory functions used with the machining program (hereinafter referred to as G code) for a lathe system (turning system) are different from those for a milling system in architecture. A turning program can be created by using G code commands for turning, while a milling program must be created by using only G code commands for turning because G code commands for milling are unavailable. Accordingly, there existed the following disadvantages:
(a) Since only G code commands for turning are available, a milling program is more difficult to create than a numerical control apparatus for a milling-only machine.
(b) A conventional milling program which has been used heretofore cannot be used for such a composite machine without modifications. Another program must be created by using turning commands only.
(c) A G code command for turning may be different from that for milling in meaning (operation), even if those have the same G code number. For example, G code commands xe2x80x9cG90xe2x80x9d and xe2x80x9cG92xe2x80x9d for milling are an absolute command and a command for coordinate system setting, respectively, but those commands for turning mean a single outline cutting cycle and a single thread cutting cycle, respectively. Moreover, some G codes are used only for milling but not used for turning and vice versa. This may create confusion for programmers in creating machining programs.
It is an object of the present invention to provide a numerical control apparatus for a composite working machine, which can handle not only G code commands for turning but also those for milling to facilitate the creation of machining programs.
A numerical control apparatus according to the present invention comprises numerical control function for turning and that for milling and also mode switching means for switching between the turning mode and the milling mode depending on a mode switching command contained in a machining program so that the numerical control function for turning or milling can be performed for the selected mode. The numerical control apparatus further comprises means for automatically switching display data on a display screen when the mode is selectively switched.
The present invention allows a single numerical control apparatus to control both turning and milling. In particular, a single machining program according to the present invention can include turning-related commands and milling-related commands, thereby facilitating the creation of machining programs.
In addition, a conventional machining program which has been used heretofore for either turning or milling can be used with the present numerical control apparatus without modifications. G code commands for turning and those for milling can have apparently discriminable formats, which can avoid undesirable confusion about the G code formats.
A single machining program can cause the working machine to perform both turning and milling without the need for creating two programs for respective processes. Therefore, machining programs can be easily maintained because the manager has to manage only a single system of programs.